A comprehensive review of the models on the nanostructure of calcium silicate hydrates

Papatzani, Styliani; Paine, Kevin; Calabria-Holley, Juliana

doi:10.1016/j.conbuildmat.2014.10.029

Cited by 136 publications

(69 citation statements)

References 105 publications

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“…The nano-granular nature of C-S-H is experimental verified by atomic force microscopy (AFM) (Nonat 2004) and nano-identification (Vandamme and Ulm 2009;Jones and Grasley 2011), as well as theoretically proven by molecular dynamics simulation (Pellenq et al 2008). However, different experiments or simulations give different particle sizes of C-S-H (Papatzani et al 2015).…”

Section: Jennings and Hismentioning

confidence: 99%

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Creep Mechanisms of Calcium–Silicate–Hydrate: An Overview of Recent Advances and Challenges

2015

International Journal of Concrete Structures and Materials

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A critical review on existing creep theories in calcium-silicate-hydrate (C-S-H) is presented with an emphasis on several fundamental questions (e.g. the roles of water, relative humidity, temperature, atomic ordering of C-S-H). A consensus on the rearrangement of nanostructures of C-S-H as a main consequence of creep, has almost been achieved. However, main disagreement still exists on two basic aspects regarding creep mechanisms: (1) at which site the creep occurs, like at interlayer, intergranular, or regions where C-S-H has a relatively higher solubility; (2) how the structural rearrangement evolutes, like in a manner of interlayer sliding, intra-transfer of water at various scales, recrystallization of gelled-like particles, or dissolutiondiffusion-reprecipitation at inter-particle boundary. The further understanding of creep behavior of C-S-H relies heavily on the appropriate characterization of its nanostructure.

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Section: Jennings and Hismentioning

confidence: 99%

“…3). A more comprehensive review on nanostructure of C-S-H can be found in the literature (Papatzani et al 2015).…”

Section: Nanostructure Of Calcium Silicate Hydratementioning

confidence: 99%

Creep Mechanisms of Calcium–Silicate–Hydrate: An Overview of Recent Advances and Challenges

2015

International Journal of Concrete Structures and Materials

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“…The calcium-silicate-hydrate (C-S-H) gel is the main hydrated phase in PC pastes, and it is the main constituent responsible for the strength and durability of the resulting mortars and concretes. However, there is still controversy about the atomic structure of the C-S-H gel, and consequently, many recent works have reviewed and addressed this issue [9][10][11].…”

Section: Cementsmentioning

confidence: 99%

Synchrotron Radiation Pair Distribution Function Analysis of Gels in Cements

et al. 2017

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Abstract:The analysis of atomic ordering in a nanocrystalline phase with small particle sizes, below ≈5 nm, is intrinsically complicated because of the lack of long-range order. Furthermore, the presence of additional crystalline phase(s) may exacerbate the problem, as is the case in cement pastes. Here, we use the synchrotron pair distribution function (PDF) chiefly to characterize the local atomic order of the nanocrystalline phases, gels, in cement pastes. We have used a multi r-range analysis approach, where the~4-7 nm r-range allows determining the crystalline phase contents; the~1-2.5 nm r-range is used to characterize the atomic ordering in the nanocrystalline component; and the~0.2-1.0 nm r-range gives insights about additional amorphous components. Specifically, we have prepared four alite pastes with variable water contents, and the analyses showed that a defective tobermorite, Ca 11 Si 9 O 28 (OH) 2 ·8.5H 2 O, gave the best fit. Furthermore, the PDF analyses suggest that the calcium silicate hydrate gel is composed of this tobermorite and amorphous calcium hydroxide. Finally, this approach has been used to study alternative cements. The hydration of monocalcium aluminate and ye'elimite pastes yield aluminum hydroxide gels. PDF analyses show that these gels are constituted of nanocrystalline gibbsite, and the particle size can be as small as 2.5 nm.

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“…Further studies on quaternary cement formulations with reduced PC content necessitate the current study in order to better understand the effect of the specific, commercial nS dispersion, which also contains polycarboxylates. For this reason, apart from the w/b ratio of 0·3, which is a suitable ratio for nS-enhanced pastes Papatzani, 2016;Papatzani et al, 2014aPapatzani et al, , 2014bPapatzani et al, , 2015, two lower ratios were also investigated -w/b of 0·2 and 0·22 -in an effort to draw the limit between enhancements and limitations. The main results are presented below.…”

Section: Spectrummentioning

confidence: 99%

Polycarboxylate/nanosilica-modified quaternary cement formulations – enhancements and limitations

Paine

2018

Advances in Cement Research

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2The effect of polycarboxylate/nanosilica (nS) particles in quaternary cement formulations comprising Portland cement (PC), limestone powder (LS) and fly ash (FA) was investigated for the first time. The reference formulation contained 60% PC, 20% LS and 20% FA by mass of binder in an effort to minimise clinker and maximise the other constituents. nS particles were characterised by way of transmission and X-ray scanning electron microscopy (SEM). The nS was added at 0·3 or 0·6% by mass as a partial replacement for PC and different water-to-binder (w/b) ratios were explored. Compressive strength tests and thermal gravimetric analyses (TGA) performed at day 7, 28 and 56 testified to pozzolanic behaviour. Results suggest a mechanism of 'de-activation' of some FA particles with age. A new ratio: (compressive strength in MPa)/(calcium hydroxide content detected by TGA) was introduced, correlating microscale characteristics (hydration products) and macroscale performance (delivered compressive strengths). Back-scattered SEM images confirmed the calcium-silicate-hydrate (C-S-H) network formation, the presence of reacted/unreacted FA particles and the availability of calcium hydroxide for delayed hydration reactions. Tests on mortars also confirmed the enhancement offered by nS addition. The lower bound nS addition was determined to be 0·6% by mass of binder for pastes and 0·5% for mortars.Notation D relative density m a mass of specimen in air m w apparent mass of specimen immersed in water w/b water-to-binder ratio ρ w density of water

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A comprehensive review of the models on the nanostructure of calcium silicate hydrates

Cited by 136 publications

References 105 publications

Creep Mechanisms of Calcium–Silicate–Hydrate: An Overview of Recent Advances and Challenges

Creep Mechanisms of Calcium–Silicate–Hydrate: An Overview of Recent Advances and Challenges

Synchrotron Radiation Pair Distribution Function Analysis of Gels in Cements

Polycarboxylate/nanosilica-modified quaternary cement formulations – enhancements and limitations

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